Why does Dally embarrass the girls at the drive-in?

Cherry Valance and Marcia are Soc. girls that Johnny and Pony meet at the drive-in. Johnny and Pony find the girls attractive and nice. They start a conversation but are embarrassed when Dally shows up. Dally is quite rude to the girls with sexual innuendo. Although Dally isn't mean, the girls are Socs and fair game to him. Johnny and Ponyboy feel that Dally is only living up to the stereotype of "hoodlum" greasers that Socs have come to expect. It also makes them look bad in front of the young ladies they have just met.